json - 遍历数组 : Cannot index array with string "" 时出现 jq 错误

Question

我正在尝试遍历 all 索引中包含的所有元素。这是我的 json 字符串:

{  
   "all":[  
      {  
            "id":"51a"
      },
      {  
            "id":"52b"
      },
      {  
            "id":"53c"
      }
    ]
}

我尝试使用 jq 进行迭代:

for id in $(jq '.all.id | keys | .[]' <<< "$json"); do
    echo "$id"
done

但我收到以下错误:

jq: error (at :9): Cannot index array with string "id"

我希望得到以下输出:

51a
52b
53c

Answer 1

像那样:

for id in $(jq -r '.all[].id' <<< "$json"); do
    echo "$id"
done

请注意，如果要删除双引号，必须使用 -r 选项:

 ·   --raw-output / -r:

       With this option, if the filter´s result is a string then
       it will be written directly to standard output rather than
       being formatted as a JSON string with quotes. This can be
       useful for making jq filters talk to non-JSON-based
       systems.

整个脚本看起来像这样:

#!/usr/bin/env bash

json='{  
   "all":[  
      {  
            "id":"51a"
      },
      {  
            "id":"52b"
      },
      {  
            "id":"53c"
      }
    ]
}'

for id in $(jq -r '.all[].id' <<< "$json"); do
    echo "$id"
done

但如评论中所述，for x in $(...) 是一种反模式，不应使用:https://mywiki.wooledge.org/DontReadLinesWithFor .

将两个索引分配给 2 个单独的变量:

#!/usr/bin/env bash

json='{
   "all":[
      {
            "id":"51a",
            "name":"Steve"
      },
      {
            "id":"52b",
            "name":"Phoebe"
      },
      {
            "id":"53c",
            "name":"Dino"
      }
    ]
}'

jq -r '.all[] | .id + " " + .name' <<< "$json" |
    while read -r id name; do
        echo id: "$id"
        echo name: "$name"
    done